A lead-acid battery used in an automobile or the like has, for suppressing rising of an internal pressure of the battery, a structure for discharging a gas generated in a container. For example, Japanese patent No. 5521390 (patent literature 1) discloses a structure where an exhaust sleeve portion and an exhaust chamber are formed between a middle lid and an upper lid which seal the container. A gas generated in the container is discharged to the outside through the exhaust sleeve portion and the exhaust chamber. Further, in patent literature 1, a gradient which is inclined toward a return flow hole is imparted to a bottom surface of the exhaust chamber and solution droplets in the exhaust chamber are made to return to the container through the return flow hole.